<!DOCTYPE html>
<html>
  <head>
    <title>My WebSocket</title>
  </head>

  <body>
    Welcome<br />
    <input id="text" type="text" /><button onclick="send()">Send</button>
    <button onclick="openWebSocket()">open</button>
    <button onclick="closeWebSocket()">Close</button>
    <div id="message"></div>
  </body>

  <script type="text/javascript">
    var websocket = null;

    //判断当前浏览器是否支持WebSocket
    if ("WebSocket" in window) {
      websocket = new WebSocket("ws://localhost:8080/websocket");
    } else {
      alert("Not support websocket");
    }

    //连接发生错误的回调方法
    websocket.onerror = function() {
      setMessageInnerHTML("error");
    };

    //连接成功建立的回调方法
    // websocket.onopen = function(event) {
    //   setMessageInnerHTML("open");
    // };

    //接收到消息的回调方法
    websocket.onmessage = function(event) {
      setMessageInnerHTML(event.data);
    };

    //连接关闭的回调方法
    websocket.onclose = function() {
      setMessageInnerHTML("close");
    };

    //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
    window.onbeforeunload = function() {
      websocket.close();
    };

    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
      document.getElementById("message").innerHTML += innerHTML + "<br/>";
    }

    function openWebSocket() {
      //连接成功建立的回调方法
      websocket.onopen = function(){
        setMessageInnerHTML("重新打开链接");
      }
    }

    //关闭连接
    function closeWebSocket() {
      websocket.close();
    }

    //发送消息
    function send() {
      var message = document.getElementById("text").value;
      websocket.send(message);
    }
  </script>
</html>
